1. Field of the Invention
The present invention concerns the field of sludge disposal from sewage treatment plants. In particular, the system hereof accurately determines the biosolid loading on a plot of land used as a disposal site.
2. Description of the Prior Art
Publicly owned treatment works for treating sewage generate considerable quantities of biosolids in the form of sludge requiring many sites for disposal. The biosolids are usually deposited on farmland as disposal sites because the biosolids are rich in organic matter and other plant nutrients such as nitrogen, phosphorus and potassium, and provide a very beneficial way to improve the land for farming. The biosolids, however, also contain various metals and regulatory authorities place limits on the amounts of the metals that may be deposited on a site. Additionally, the amount of biosolids deposition must also be limited for nitrogen, phosphorus and potassium so that allowable levels are not exceeded for the next crop to be grown on the site. As regulatory authorities demand higher levels of accuracy and reporting concerning the quantity and quality of the biosolids disposal, the administrative requirements have become burdensome, expensive, and in some cases, unmanageable.
One source of problems has been the lack of accurate land coordinates of the disposal sites for precisely locating the sites so that disposal does not occur within regulated minimum distances from a land features such as wells, dwellings and bodies of water. Furthermore, accurate coordinates are required for precisely determining the area of the site so that biosolids loading can be accurately calculated on a per unit basis.
In the prior art, disposal operators have used topographic maps to draw by hand the boundaries of a site based on approximations and to locate various land features. A planimeter has been used to determine the area of the site. As those skilled in the art of cartography appreciate, these techniques lead to substantial inaccuracies, but no practical alternatives have been available.